The invention relates to a control arrangement for washing machines, in particular clothes washing machines or combined clothes washing and drying machines, said control arrangement being associated with the detergent dispensing means of the washing machine and adapted to selectively control the addition into the machine's tub of the various detergent products provided for pre-washing and washing the clothes, while at the same time automatically signalling the corresponding control position of the dispenser.
Detergent dispensers for washing machines such as clothes washing machines and/or combined clothes washing and drying machines are known in the prior art, which are divided into a number of separate compartments intended for holding the various pre-wash and main wash detergents, as well as the various rinsing aids such as the bleaching agent and/or the fabric conditioner, wherein each such compartment is capable of being selectively flushed by the water flowing in from the supply mains and directed into said compartment by means a suitable rotating compartment selector means, which is capable of being displaced into its various operational positions by suitable linkage means operable by one or several profiled cams of the program-sequence/timer control of the washing machine to thereby cause the water to flow into the wash tub of the machine together with the detergent or rinse aid contained in the compartment being from time to time flushed.
Detergent dispensers are also known from the prior art, which are intended for use in combination with electronic washing machines provided with microprocessor means to control each single washing process in all its various phases, wherein the compartments of the detergent dispenser are designed so as to be capable of being flushed with the in-flowing water through respective conduits individually controlled by shut-off devices such as electromagnetic shut-off valves or the like, each one of said shut-off devices being associated with the microprocessor control circuit so as to cause, when energized by the microprocessor, the in-flowing water to flush the compartment associated with said electrically actuated shut-off device and flow into the washing machine tub together with the detergent contained therein.
Further known types of detergent dispensers for use in combination with electronic washing machines provided with microprocessor control means and rotating compartment selector means of the aforementioned type, also comprise two plungers connected with the rotating compartment selector means so as to displace it into its various control positions, each one of said plungers containing wax capable of being heated by a PTC thermistor element to be electrically supplied through such a solid-state semiconductor switching device as a triac or the like which is included in the electric circuitry of said washing machines together with said microprocessor control means. In such a way, the rotating compartment selector means of said detergent dispensers is displaced into its various control positions through the control action of the microprocessor means, thereby causing the detergent or rinsing aid contained in the corresponding compartment to be flushed off into the wash tub by keeping both said PTC thermistor elements either energized or de-energized, or selectively energized and de-energized, through said solid-state triac switch, owing to the different thermal expansion of the wax in the two aforementioned plungers as brought about by said energization and de-energization processes of said PTC thermistor elements.